Fossil fuel combustion and deforestation have resulted in a rapid increase in atmospheric [CO 2] since the 1950's, and it will reach about 550 mol mol -1 in 2050. Field experiments were conducted at the Free-air CO 2 Enrichment facility in Beijing, China. Winter wheat was grown to maturity under elevated [CO 2] (55017 mol mol -1) and ambient [CO 2] (41516 mol mol -1), with high nitrogen (N) supply (HN, 170 kg N ha -1) and low nitrogen supply (LN, 100 kg N ha -1) for three growing seasons from 2007 to 2010. Elevated [CO 2] increased wheat grain yield by 11.4% across the three years. [CO 2]-induced yield enhancements were 10.8% and 11.9% under low N and high N supply, respectively. Nitrogen accumulation under elevated [CO 2] was increased by 12.9% and 9.2% at the half-way anthesis and ripening stage across three years, respectively. Winter wheat had higher nitrogen demand under elevated [CO 2] than ambient [CO 2], and grain yield had a stronger correlation with plant N uptake after anthesis than before anthesis at high [CO 2]. Our results suggest that regulating on the N application rate and time, is likely important for sustainable grain production under future CO 2 climate.
